Many efforts have been made to provide practical apparatus and method for deheading shrimp. Shrimp trawlers, especially the larger ones, go to sea for a number of weeks during which time it is necessary to refrigerate the catch of shrimp. Before putting the shrimp on ice or otherwise refrigerating them, it is necessary that the heads be removed. Deheading shrimp is a time consuming job requiring that personnel be taken along for carrying out the deheading operation in addition to the crew necessary for the operation of the trawler and nets.
An early effort to provide a shrimp deheading machine is described in U.S Letters Pat. No. 1,367,546 wherein deheading apparatus includes a sharp, fixed knife for deheading shrimp carried thereto in a transverse horizontal position in open conveyor compartments. Such apparatus has the advantage of deheading shrimp through a shearing action of sorts but the difficulty inherent in positioning the shrimp in the compartments carried by the conveyor and maintaining them so positioned under engagement with the blade has evidently rendered the device impractical.
It is more often the case that a rotating, sharp knife is used for severing the heads of shrimp from the bodies as illustrated in U.S. Letters Pat. No. 3,698,038. The device of this patent is somewhat similar to that just described above except that the cutting blade rotates. This more complicated apparatus possesses a disadvantage, therefore, in that there is less tendency to remove undesirable parts of the shrimp and it is more likely that part of the meat of the body portion may be severed by the sharp blade and discarded together with the head. Some of the other efforts to provide a suitable shrimp deheading mechanism are illustrated in U.S. Letters Pat. Nos. 2,958,896, 3,281,889 and 3,451,100.
Accordingly, it is an important object of this invention to provide an apparatus and method facilitating the deheading of raw shrimp which will obviate the necessity for taking persons in addition to the regular crew on extended trips at sea for the purpose of deheading the shrimp catch.
Another important object of the invention is the provision of a sizing apparatus wherein shrimp whether headed or deheaded, raw or cooked, may be accurately sized through a simple method and employing a minimum of moving parts.
Another important object of the invention is the provision of a deheading apparatus which may be operated independently of the sizing apparatus and which permits shrimp which have already been sized to be deheaded through the use of a shearing action which results in the removal of part of the intestines of the shrimp together with the head.
Another object of the invention is the provision of a versatile apparatus which may be used for sizing or deheading or both and which is adaptable to use at sea as well as in the plant.
The machine may also be used at receiving stations where shrimp are off-loaded from boats for deheading and marketing. The costs of deheading, now done manually, could be appreciably reduced by using a machine constructed in accordance with the present invention. The "deheaders" now refuse to dehead the smaller sizes of shrimp which are sent to canners for processing. These smaller shrimp, when deheaded by such a machine, would be thus more readily available to those who cannot afford the larger size shrimp.